Sensor technologies advance over the past two decades, there are different types of sensors such as temperature sensor, proximity sensor, accelerometer, IR sensor (Infrared Sensor), pressure sensor, light sensor etc. Sensors have been applied to many applications product design, process optimization, and research and development.
Tactile sensors are useful in a wide variety of robot applications. There are two types of robots, namely, industrial robots and humanoid robots. Industrial robots can repeatedly perform given tasks according to a preplanned program, while humanoid robots will eventually work along humans if they understand human intelligence, and act like humans. Since humanoid robots are expected to simulate the human structure and behavior, they are more complex than industrial robots. For example, a humanoid robot is expected to reach its goal while adapting to the changes in its environment which require autonomous learning and safe interaction, among many other things, unlike industrial robots. Tactile sensors provide useful information about the state of contact between a humanoid robot hand and an object in prehension. They can indicate the presence or shape of an object, its location in the hand, and the force of contact. Tactile sensors may be of different types including piezoresistive, piezoelectric, capacitive and optical sensors. The present disclosure related to optical sensors in general, optical sensors have advantages of no cable and anti-electromagnetic interference, and they are divided into direct and indirect optical sensing method. Direct optical sensing method uses optical fiber to sense the reflected light intensity to determine the magnitude of the tactile pressure. While the indirect optical sensing methods need no optical fiber to sense the reflected light intensity to determine the magnitude of the tactile pressure. Therefore, the present disclosure is further related to an indirect optical sensing method in particular.
Some related art introduced a piezoresistive pressure tactile sensor robot system comprising a hand with a tactile sensor, a tactile information processing unit, a robot controller, etc., wherein the sensing unit of the tactile sensor is composed of a plurality of pressure sensors, respectively detecting the pressure and a plurality of pressure sensors, each detecting its spatial position. Other related arts disclosed a sensing device combining a piezoresistive and capacitive haptic function, wherein the dielectric material layer comprises an elastic colloidal material, and a capacitance detecting circuit sequentially or randomly applies a touch capacitive sensing excitation signal to the selected first sensing electrode for proximity and touch detection operations; In the proximity and touch detection operation, it is assisted by the inductive excitation signal of the touch capacitor, a signal is applied to the opposite at least one second electrode; during the pressure detecting operation, a pressure capacitive sensing excitation signal is applied to the at least one second sensing electrode, and a corresponding excitation signal is sequentially or randomly applied to the selected one. Therefore, the present disclosure provided a tactile sensor that sensed reflected light to determine the presence of an object which few or none of the related art disclosed.